Islamist insurgents retreating from Timbuktu set fire to a library containing thousands of priceless historic manuscripts, according to the Saharan town's mayor, in an incident he described as a "devastating blow" to world heritage.

Hallé Ousmani Cissé told the Guardian that al-Qaida-allied fighters on Saturday torched two buildings that held the manuscripts, some of which dated back to the 13th century. They also burned down the town hall, the governor's office and an MP's residence, and shot dead a man who was celebrating the arrival of the French military.

French troops and the Malian army reached the gates of Timbuktu on Saturday and secured the town's airport. But they appear to have got there too late to rescue the leather-bound manuscripts that were a unique record of sub-Saharan Africa's rich medieval history. The rebels attacked the airport on Sunday, the mayor said.

"It's true. They have burned the manuscripts," Cissé said in a phone interview from Mali's capital, Bamako. "They also burned down several buildings. There was one guy who was celebrating in the street and they killed him."

The Malian army, backed by French forces, is trying to drive rebels from cities they took over last year.

Read more about the fighting at the Guardian, and about Timbuktu's treasures on The Root.